1. Field of the Invention
This invention relates to an endoscope angling mechanism for bending a rigid portion at the tip end of an insert section of an endoscope arcuately into desired directions.
2. Description of the Prior Art
Endoscopes are in wide use for medical and industrial purposes, for example, for internal examination or diagnosis of patients' bodies, engines, nuclear reactors or other equipments, or for therapeutic or repairing treatments with use of concurrently inserted forceps or other instruments.
For understanding the status of the prior art, FIGS. 7 and 8 schematically illustrate the general construction of an endoscope of this sort and the construction of a prior art angling mechanism, respectively. In these figures, indicated at 1 is an insert section and at 2 is an operating section of the endoscope. The insert section 1 is successively composed of: a flexible portion 1a which forms a major part of the insert section 1 in proportion, extending contiguously from the operating section 2 of the endoscope and being smoothly flexible in conformity with the shape of the path of insertion of the endoscope; an angle portion 1b connected to the fore end of the flexible portion 1a; and a rigid tip end portion 1c connected to the fore end of the angle portion 1b.
In this instance, the angle portion 1b has a joint ring structure which is composed of a plural number of pivotally connected angle rings 3 and which can be bent in a desired direction. Namely, the rigid portion 1c at the distal end can be turned into a desired direction when introducing the insert section 1 into a body along a path of insertion or when changing the field of view of observation. For bending the angle portion 1b in this manner, an angling mechanism is provided in association with a knob section to be manipulated by the operator.
As shown in FIG. 8, the angling mechanism of this sort usually employs a pair of upper and lower operating wires 4a and 4b (or a pair of upper and lower wires plus a pair of left and right wires) within the angle rings 3 in the angle portion 1b. Each of these operating wires 4a and 4b has the fore end thereof securely stopped on an angle ring 3a in the foremost position (or to the distal end of the rigid portion 1c), and the other end extended into the operating section 2 and wound on an angle drum 5. The angle drum 5 is mounted on a rotational shaft 6 which is led out of the housing of the operating section 2 and coupled with an angle knob 7. Accordingly, as the angle knob 7 is turned by an operator, the operating wires 4a and 4b are pulled to and fro to bend the angle portion 1b as indicated by imaginary line in FIG. 7.
However, in a case where the angle portion 1b is arranged to be bent in its entirety by the angling operation as described above, difficulties are encountered, for example, in changing the field of view of observation in a narrow intracorporeal cavity or the like. For the purpose of overcoming such a problem, there has been developed an endoscope with an angle portion 1b which has a higher rigidity toward its base end in such a way that it is bendable only in its fore end portion in an initial stage of the angling operation and becomes bendable toward the rigid base end portion and finally in its entire body in proportion to the magnitude of the applied angling efforts. This angle construction has a problem that the load of the angling operation is increased to such an extent as to impair smooth operation of the angle knob.